It is sometimes necessary to transfer articles carried on a conveyor system from one conveyor line to another, as from a main line to a branch or spur line or vice versa. Often, it is convenient to power the conveyor elements in at least a transition section between branching conveyors from a single motor member, such as a motor member which drives the main conveyor line. Such arrangements occur in many types of conveyors, such as belt conveyors and roller conveyors, whether the rollers are driven by a belt, a cable, or by a line shaft.
In a line shaft driven roller conveyor, power is transmitted from a rotary motor to the conveyor rollers by an elongated drive shaft, usually termed a line shaft, which is rotatably supported along the main conveyor. Small endless belts, called O-rings, extend from the line shaft to each roller or to groups of rollers to transmit rotation thereto.
In the past when a line shaft driven branch conveyor is powered from a main conveyor line shaft, it is common to transfer power through a gear unit or through a universal joint arrangement, often in combination with an intermediate shaft driven by the main line shaft. These arrangements are relatively expensive, generally noisy, and often generate vibrations.
It is common to transfer rotation between shafts by the use of endless belts. When the shafts are parallel, belts of virtually any cross section may be employed, such as round, vee, or flat cross section belts. When it is desired to positively rotate the driven shaft at a selected fraction or multiple of the driving shaft speed, toothed belts of vee or flat (rectangular) cross section in combination with toothed pulleys or gears on the shafts are employed. When the shafts are not parallel, the belts must undergo twisting in transition between the shafts. In such situations, it is the usual practice to use round cross section belts since there are difficulties encountered in twisting vee and flat cross sectional belts and maintaining the belts on their pulleys. The usual alternative when positive drive is desired between nonparallel shafts is to use angled gear boxes or universal joints as mentioned above.